Heat pump system and method for monitoring valve leaks in a heat pump system

ABSTRACT

Heat pump system ( 100 ) comprising a heat medium circuit ( 210,220,230,240,250,310,320,410,420,430,440,450,460 ) in turn comprising at least three heat exchanging means ( 314,315,315,422,433,452 ) between the heat medium and a respective heat source or sink selected from outdoor air, a water body, the ground, indoorair, pool water or tap water, a valve means ( 311,312,313,421,431,451 ) arranged to selectively direct the heat medium to at least two of said heat exchanging means, and a control means ( 500 ). The invention is characterized in that the heat pump system comprises temperature sensors ( 314   a,   314   b;   315   a,   315   b;   316   a,   316   b;   423,424,425;432,434,435 ) both upstream and downstream of at least one of said heat exchanging means, in that the system determines, based upon temperature measurement values comprising at least onevalue read from said sensors, to what heat exchanging means the heat medium is to be directed, and in that when heat medium is not directed to a certain heat exchanging means a measured temperature value is read upstream and downstream of the certain heatexchanging means, and in that an alert is set off in case the values differ by more than a predetermined value. The invention also relates to a method.

The present invention relates to methods and systems for heat pumping.In particular, it relates to such methods and systems in which one orseveral primary heat sources or sinks are interconnected to one orseveral secondary heat sources or sinks, so as to provide flexible andresponsive heating and/or cooling of a construction.

There are many known solutions for providing heat and/or cold to abuilding using heat pumping. For instance, bore holes, earth or a waterbodies can be used to provide a heat carrier with stable temperature,which heat carrier can be used to heat water or indoors air, or to coolindoors air, using heat pumping. Similarly, outdoors air can be used toheat or cool a heat carrier, which heat carrier can then be used, viaheat pumping, to heat water or indoors air, or to cool indoors air. Suchheat pumping provides efficient heating or cooling, which is well knownin the art.

Heat pumping as such has also been described extensively in the priorart. For instance, reversible heat pumps are known, as are heat pumps ofdifferent types.

One such example is a liquid-liquid heat pump, arranged to, via aninternal heat medium loop, transfer thermal energy from one liquid toanother liquid. Another example is an air-liquid heat pump, arranged to,via a similar internal heat medium loop, transfer thermal energy fromair to a liquid or vice versa.

It is further known to “charge” an energy storage used for cooling withcold by heat exchanging between cold outdoors air and the energystorage.

A problem when designing a heat pump system for a building is that theheating and/or cooling requirements typically fluctuate heavily acrossthe year, and even over a single day. For instance, during the summer intemperate climates the need for heating may be close to zero, while theneed for heating during the winter may be substantial. Similarly, theneed for cooling may be intermittent during the summer in such climates,while an outdoor pool may simultaneously need heating. Further, the needfor hot tap water may vary depending on the time of day.

Hence, the required maximum capacity of a heat pumping system istypically much higher than an average requirement of the system. Thiscan, for instance, be solved using an accumulation tank, for instancethe hot tap water tank. This is problematic, since such tank needs to belarge in order to be of sufficient capacity, and since there are thermalloss associated with such storage of thermal energy. Also, it may becomplicated or cost-inefficient to transform the stored energy intosuitable heating of indoors air or pool water, whereas the need forcooling is not easily met. Also, in case the conditions for heatproduction are attractive, the accumulation tank only accepts a certainamount of thermal energy before its temperature reaches its maximumallowed value. For instance, hot tap water can be only 100° C. hot.

Another solution that has been proposed is to use a heat pump with lessthan the maximum required capacity, and to supplement it with anelectrical heating device which can be activated together with the heatpump in order to reach the highest production powers required for thebuilding in question.

Such electrical heating is expensive, and is also a less attractivesolution from an environmental point of view, as compared to using heatpumping. However, an over-dimensioned heat pump is also expensive andmay not perform at maximum efficiency at the relatively low powerrequired in most situations.

Furthermore, there is a problem with geothermal bore holes being cooleddown during the summer, due to excess heating of houses, leading to theground in general becoming cooler over time, in particular at sites withmany such bore holes. This, in turn, leads to decreased heatingefficiency using such geothermal heating systems.

Hence, there is a need for a flexible and simple heat pump system whichcan optimally distribute thermal energy between a building and itsenvironment at high average efficiency.

There is also a need to monitor a heat pump system in a morecost-efficient manner than what is the case with conventional heat pumpsystems. In particular, heat pump systems can become quite complex, withnumerous valves and other components. It is often difficult to detectdamage to such components without performing a regular inspection. Itwould be desirable to automate such inspection, with the aim ofdetecting component damage at an early point before more severe damageresults.

The present invention solves the above described problems.

Hence, the invention relates to a heat pump system comprising a heatmedium circuit in turn comprising at least three heat exchanging meansarranged to transfer thermal energy between the heat medium and arespective heat source or sink selected from outdoor air, a water body,the ground, indoor air, pool water or tap water, a valve means arrangedto selectively direct the heat medium to at least two of said heatexchanging means, and a control means arranged to control said valvemeans, which method is characterized in that the heat pump systemcomprises respective temperature sensors both upstream and downstream ofat least one of said heat exchanging means, in that the control means isarranged to, based upon temperature measurement values comprising atleast one value read from said sensors, determine to what heatexchanging means the heat medium is to be directed, and in that whenheat medium is not directed to a certain heat exchanging means thecontrol means is arranged to read a measured temperature value upstreamand downstream of the certain heat exchanging means, to compare thesevalues to each other and to set off an alert in case the values differby more than a predetermined value.

The invention also relates to a method for monitoring valve leaks in aheat pump system comprising a heat medium circuit in turn comprising atleast three heat exchanging means arranged to transfer thermal energybetween the heat medium and a respective heat source or sink selectedfrom outdoor air, a water body, the ground, indoor air, pool water ortap water, a valve means arranged to selectively direct the heat mediumto at least two of said heat exchanging means, and a control meansarranged to control said valve means, which method is characterized inthat the heat pump system comprises respective temperature sensors bothupstream and down-stream of at least one of said heat exchanging means,in that the method comprises a step in which the control means readstemperature measurement values comprising at least one value read fromsaid sensors and, based upon these values, determines to what heatexchanging means the heat medium is to be directed, and in that themethod further comprises a step in which, when heat medium is notdirected to a certain heat exchanging means the control means reads ameasured temperature value upstream and down-stream of the certain heatexchanging means, compares these values to each other and sets off analert in case the values differ by more than a predetermined value.

In the following, the invention will be described in detail, withreference to exemplifying embodiments of the invention and to theenclosed drawings, wherein:

FIG. 1a is an overview diagram of a heat pump system according to afirst embodiment of the invention showing circulation in a firstcirculation pattern;

FIG. 1b is an overview diagram of a heat pump system according to thesaid first embodiment of the invention showing circulation in a secondcirculation pattern;

FIG. 1c is an overview diagram of a heat pump system according to thesaid first embodiment of the invention showing circulation in a thirdcirculation pattern; and

FIG. 1d is an overview diagram of a heat pump system according to thesaid first embodiment of the invention showing circulation in a fourthcirculation pattern.

All figures share the same reference numerals for the same orcorresponding parts.

FIGS. 1a and 1b show a heat pump system 100 according to a preferredembodiment of the invention. The heat pump system 100 comprises a heatpump part 200, comprising an inner loop heat medium circuit 210, 220,230, 240, 250 in which an inner heat medium is circulated. The innerloop heat medium circuit comprises at least one compressor 211 and atleast one expansion valve 232, 242 (in the exemplifying embodimentsillustrated figures, there are two expansion valves, for reasonsexplained below).

The heat pump system 100 is preferably arranged to heat and/or cool aconstruction, preferably being or comprising a building, such as anapartment building or an office or other commercial building, butpreferably a small one- or two family house. Such a construction mayalso comprise parts to be heated and/or cooled that are peripheral tosuch a building, but still part of the same construction or real estate,such as an outdoor pool 342 arranged next to such a building.

Furthermore, the heat pump system 100 comprises or is associated with aprimary side part 400 and a secondary side part 300. At the primaryside, heat exchange is performed between a primary-side heat medium andvarious external sources of heat and/or cold; at the secondary side,heat exchange is performed between a secondary-side heat medium andvarious heat and/or cold consuming devices. Hence, thermal energy may betransported to or from the primary side 400, via the heat pump part 200,from or to the secondary side 300, depending on the requirements of heator cold of the said consuming devices. The heat pump part 200 performsheat pumping action during the course of this transfer of thermalenergy, as opposed to only performing heat exchanging. As will beexemplified below, thermal energy may also be provided directly betweenthe primary side 400 and the secondary side 300, using heat exchangewithout any heat pumping action.

As illustrated in FIGS. 1a and 1 b, it is preferred that the primaryside 400 comprises a heat medium circuit 410, 420, 430, 440, 450, 460which is separated from the inner loop heat medium circuit 210, 220,230, 240, 250, wherein these two circuits communicate thermally witheach other via a heat exchanger 214. Even though it is preferred thatthe heat exchanger 214, as well as heat exchanger 215 (see below) may bepart of the inner loop 200, one or both of these may form part of part400, 300, respectively.

However, the circuits 210, 220, 230, 240, 250 and 410, 420, 430, 440,450, 460 may alternatively be one and the same circuit, sharing one andthe same heat medium. Separating the two circuits as is illustrated inFIGS. 1a and 1b is advantageous in some embodiments, since it is thenpossible to select a suitable respective inner loop and primary-sideheat media with greater freedom, so that one suitable heat medium can beused in the internal heat pump circuit 210, 220, 230, 240, 250, and adifferent suitable heat medium can be used in the primary side circuit410, 420, 430, 440, 450, 460, the latter typically having differenttemperature requirements etc. than the former. On the other hand, byhaving only one circuit, the circulation pump 461 may for instance beomitted, leading to lower costs, and the unnecessary losses in the heatexchanger 214 may be cut. Further, the conduit in circuit 220 may haveto withstand considerable pressure, which may not be the case for thecircuit 460, making the system 100 less costly with the circuit 220separated from the circuit 460.

Similarly, the secondary side 300 comprises a heat medium circuit 310,320 which (as shown in the figures) preferably is isolated but which maybe shared with the inner loop heat pump circuit 210, 220, 230, 240.Through the secondary-side circuit 310, 320, a secondary-side heatmedium flows, which is heat exchanged to the inner loop heat mediumflowing through the internal heat pump circuit 210, 220, 230, 240, 250using heat exchanger 215. The flow in circuits 310, 320 is driven by acirculation pump 317.

From the above, it is clear that there are three main conduitcircuits—the primary-side 400 circuit 410, 420, 430, 440, 450, 460; thesecondary-side 300 circuit 310, 320; and the inner circuit 210, 220,230, 240, 350. For many applications, the configuration illustrated inFIG. 1a is preferred, namely that the three main conduit circuits areseparated in terms of respective heat medium flow paths. However, eitherthe primary-side circuit and/or the secondary-side circuit may beinterconnected with the inner circuit in a way so that these circuitscommunicate, in particular so that they actually form a connected loopcircuit through which respective heat medium flows in a loop manner.Hence, the primary-side heat medium and the inner loop heat medium maybe one and the same; and the secondary-side heat medium and the innerloop heat medium may be one and the same. In some cases, it is realizedthat all three—the primary-side heat medium; the secondary-side heatmedium; and the inner loop heat medium—may be one and the same heatmedium, circulated in one and the same connected circuit loop 310, 320,210, 220, 230, 240, 250, 410, 420, 430, 440, 450, 460. It is alsopossible that the said circuits are separated all three, possibly withthree different respective heat media.

In the following, all these possibilities are considered applicable whenso is possible and desired for various reasons.

According to a preferred embodiment, at least two primary heatexchanging means 422, 433, 452 are arranged to transfer thermal energybetween the primary-side heat medium and at least one of two differentprimary heat sources or sinks selected from outdoor air, a water body,the ground or exhaust air from the construction. In this context, “theground” can be a bore hole 431 such as the one illustrated in thefigures, but may alternatively or additionally be, for instance, ashallowly buried collector conduit beneath a lawn or the like.

In the figures, the said primary heat sources or sinks are exemplifiedby the outdoors air near the construction to be heated and/or cooled, inthat an air heat exchanger 422, such as fan convector, is arranged totransfer thermal energy to said outdoors air from the secondary-sideheat medium or vice versa; the ground, in that a collector conduit 433is arranged in a bore hole 431, and arranged to transfer thermal energyto the ground surrounding the hole 431 from the secondary-side heatmedium flowing through the conduit 433 or vice versa; and exhaust airfrom the construction, in that a heat exchanger 452 is arranged totransfer thermal energy from the exhaust air in an exhaust air pipe 453to the secondary-side heat medium. Said exhaust air is preferablyventilated air from a building.

Herein, the expression “primary heat exchanging means” relates to a heatexchanging means arranged to achieve thermal energy transfer between theprimary-side heat medium and a primary heat source or sink arranged sothat it does not substantially affect the temperature of theconstruction to be heated and/or cooled using a system according to thepresent invention. Such primary heat exchanging means may, for instance,be such means 422, 433 that are arranged outdoors or at least outside ofthe construction to be heated and/or cooled, or may operate on exhaustair leaving the construction, such as means 452. It is realized thatthere may be more than two primary heat exchanging means operatingvis-à-vis one and the same heat source or sink. Apart from the threeprimary heat exchanging means 412, 422, 433 shown in FIG. 1 a, otherexamples comprise arranging several parallel bore holes with respectivecollector conduits. Furthermore, there may also be more than two primaryheat sources or sinks that are used in parallel. In the case where thereare at least two primary heat sources or sinks, it is preferred thatthese are selected from outdoor air, a water body and the ground.

According to a preferred embodiment, there are at least one secondaryheat exchanging means 314, 315, 316, arranged to transfer thermal energybetween the secondary-side heat medium and at least one of two differentsecondary heat sources or sinks selected from indoors air, pool water,tap water and an outdoor ground or a floor in the construction. In thefigures, these secondary heat sources or sinks are exemplified by theindoors air inside the construction, in that an indoors fan convector314 is arranged to transfer thermal energy to said indoors air from thesecondary-side heat medium or vice versa; an isolated indoors liquidheating loop, in that a heat exchanger 315 is arranged to transferthermal energy to such an indoors water loop 330 serving indoorsradiators 332 or a floor heating/cooling system, from the secondary-sideheat medium, or vice versa; and the water 343 of a swimming pool 342, inthat a heat exchanger 316 is arranged to transfer thermal energy to saidwater 343 from the secondary-side heat medium or vice versa. Not shownin the figures is the option in which an outdoor ground or a floor inthe construction is heated and/or cooled. In this latter case,secondary-side heat medium is directed, using a suitable secondary-sidecircuit, to a loop in the outdoors ground or floor for heating thetopmost ground layer. For instance, the outdoors ground or floor may bea sports field requiring heating during winter in order to keep it freefrom snow and ice, or an ice hockey field requiring cooling formaintenance the ice. There may also be a heat exchanger arranged betweenthe said secondary-side circuit and the heat carrier loop arranged inthe ground.

It is realized that the illustrated secondary heat exchanging means 314,315, 316 are only examples of such secondary heat exchanging means, andfurther that such secondary heat exchanging means may also, forinstance, be connected in series or both in series and in parallel.

The water loop 330 is served by a circulation pump 331.

The pool 342 may in certain embodiments instead be a tank for hot tapwater 343, the main difference from the pool example being that thetemperature requirements for the water 343 are different—for the pool awater temperature of about 20-30° C. is typically desired, whereasconsiderably higher temperatures, such as 50-80° C. would be desired fora hot tap water tank example.

As can be seen in the figures, the secondary-side heat sources or sinksare connected in a way so that heat or cold delivered from the heat pumppart 200 can selectively be delivered to one or several of saidsecondary-side heat sources or sinks. In the figures, this isexemplified by the secondary-side heat sources or sinks being connectedin parallel, with respective shut-off valves 311, 312, 313 beingarranged to shut off either one of them in a selectable manner; and inthat the inner heat medium is circulated through theseparallel-connected conduits 310. This way, the control means 500 (seebelow) can selectively direct heat or cold from the heat pump part 200to one or several recipients of such heat or cold at the secondary side300.

Herein, the expression “secondary heat exchanging means” relates to aheat exchanging means arranged so that it may substantially affect thetemperature of the construction to be heated and/or cooled using asystem according to the present invention. Such secondary heatexchanging means may, for instance, be such means arranged to achievethermal transfer between the secondary-side heat medium and a heatsource or sink arranged indoors, or at least inside of, or within theboundaries of, a construction or real estate to be heated and/or cooledusing a system according to the present invention. In a way which isanalogous to the case for the primary heat exchanging means describedabove, there may be more than one secondary heat exchanging meansoperating vis-à-vis one and the same heat source or sink, such asseveral parallel radiator loops with their own respective heat exchangerto the secondary-side heat medium or both a direct 314 and an indirect315, 332 heat exchange towards indoors air; and there may be more thantwo secondary heat sources or sinks that are used in parallel, as isshown in the figures.

It is realized that the term “heat source or sink” is used herein torefer to some type of entity with the capacity of absorbing and emittingthermal energy, and that may therefore be used for heating or cooling arespective heat medium via heat exchange to the heat source or sinkusing a heat exchange means arranged to perform such heat exchange.Whether the heat medium is actually heated or cooled depends upon theoperating principle used at the particular instant, in particular uponthe relative temperature difference between the heat source or sink andthe heat medium. For some heat sources or sinks, such as the water of aswimming pool, only one type of thermal transfer, in that particularcase heating of the pool water by cooling the corresponding heat medium,will likely or always be performed. The corresponding is true regardingsource 452, which will likely or always cool the exhaust air hencewarming the primary-side heat medium.

It is further realized that the term “circuit” herein is used to denotea conduit arrangement through which heat medium can flow. Such a circuitmay or may not be a closed loop. A “loop circuit”, however, as usedherein, is a heat medium closed loop circuit.

Further according to a preferred embodiment, the system 100 comprises arespective temperature sensor 423, 432, 454, each arranged to measurethe temperature of a respective one of each of said primary heat sourcesor sinks. Such measurement can be performed in different ways. Oneexample is to directly measure the temperature of the heat source orsink in question, such as the sensor 423 measuring the outdoors air orthe sensor 432 measuring the bore hole 431 temperature at a particulardepth. However, it is also possible to measure the temperature of theheat source or sink in question indirectly, such as by measuring thetemperature of the primary-side heat medium after passage through theheat exchanger 422, 433, 452 passing the heat source or sink inquestion, possibly taking into consideration knowledge about how aparticular heat source or sink is expected to affect the temperature ofa heat medium flowing past the heat source or sink in question. This isthe case for temperature sensor 454, measuring the temperature of theprimary-side heat medium after passage of heat exchanger 452.

In another example, a pair 424, 425 of temperature sensors, arranged tomeasure the temperature of the heat medium upstream and downstream ofthe heat exchanger 422, are used as an alternative or in addition to thesensor 423; and a pair 434, 435 of temperature sensors, arranged tomeasure the temperature of the heat medium upstream and downstream ofthe heat exchanger 433, may also be used as an alternative or inaddition to the sensor 432. It is hence also possible to use acombination of these two basic measurement principles.

Further according to a preferred embodiment, the system 100 comprises avalve means arranged to selectively direct the primary-side heat mediumto at least one of the said primary heat exchanging means 422, 433, 452.In the figures, this valve means is exemplified by a first three-wayvalve 421, arranged to selectively direct primary-side heat medium fromcircuit 460 to either circuit 420 (past outdoors air heat exchanger 422)or directly to three-way valve 431 (without passing the heat exchanger422). Another example of said valve means is the three-way valve 431,arranged to selectively direct secondary-side heat medium from circuit460 (arriving at three-way valve 431 from three-way valve 421 or fromcircuit 420) either to circuit 430 (past bore hole 431 heat exchangingcollector conduit 433) or (via circuit 420) directly to circuit 440. Athird example is the three-way valve 451, arranged to selectively directsecondary-side heat medium from circuit 430 or 440 either to circuit450, via heat exchanger 452, or directly back to circuit 460.

It is preferred that the said valve means is arranged to completely orsubstantially completely shut off the supply of primary-side heat mediumto at least two primary heat exchanging means, in a selective manner. Inthis sense, the valve means comprises at least two of, or even allthree, three-way valves 421, 431, 451, working together as one single“valve means”.

Herein, the term “selectively directing” and “selectively shutting off”means directing the heat medium to, or shutting off heat medium accessto, one or more heat sources or sinks while at the same time notdirecting the heat medium to, or shutting off heat medium access to,other heat sources or sinks. Hence, the said valve means is arranged tocontrol to which heat sources or sinks the heat medium is directed ateach point in time.

Purely for exemplifying purposes, the arrows shown in FIG. 1a illustratethe flow when the primary-side heat medium is selectively directed onlyto the outdoors air heat exchanger 422, while the arrows shown in FIG.1b illustrate the flow when the primary-side heat medium is selectivelydirected only to the ground collector conduit 433. FIGS. 1c and 1d bothillustrate a combination of these flows, hence when both heat sources orsinks are used.

Furthermore, it is preferred that a control means 500 is arranged tocontrol said valve means 421, 431, 451, and also valve means 411 and 212(see below). The control means 500 may, for instance, be a serverarranged locally in the construction to be heated and/or cooled, or acentrally located server arranged remotely and connected to theconstruction via the internet. The control means 500 has a suitablewired and/or wireless digital communication interface with a number ofsensors and/or actuators of the system 100, which are read and/orcontrolled by the control means 500. Preferably, all sensors, valves andother readable and/or controllable equipment, such as variablecompressor 211 and variable expansion valves 232, 242, are connected tothe control means 500 in a suitable way, for reading and/or control bythe control means 500. The control means 500 preferably also has aconventional processor and a conventional database, and runs a softwarefunction for controt and administration of the heat pump system 100.Preferably, the control means 500 is connected to, and arranged toreceive data from, external data providers such as providers of localweather forecasts, for use in the control of the system 100 operation.The control means 500 is preferably also connected to various outdoorsand indoors sensors, such as temperature, air pressure, humidity,sunlight incidence, etc. sensors, which may be conventional as such andare jointly illustrated in the figures by 501. Using such external dataand sensors, the control means 500 is arranged to control the system 100with the aim of maintaining, over time, a predetermined indoorstemperature interval; a respective minimum hot tap water and pool watertemperature, and so forth, depending on settings made by a user of thesystem 100, such as remotely using a web server user interface meansprovided by the control device 500. This control function of the controldevice 500 will be exemplified in the following.

The system 100 can be run in several different modes. As used herein, ina “secondary-side heating operating mode”, thermal energy is transferredfrom at least one primary-side 400 heat source and is transferred, viaheat pump action in the part 200 and heat exchange as described above,to at least one heat consuming secondary-side 300 heat sink.Correspondingly, in a “secondary-side cooling operating mode”, thermalenergy is transferred from at least one secondary-side 300 heat sourceand is transferred, via heat pump action in the part 200 and heatexchange, to at least one primary-side 400 heat sink. In thesecondary-side cooling operating mode, thermal energy can also betransferred from the secondary side 300 to the primary side 400 withoutheat pumping, as exemplified by circuit 410 (see below).

As mentioned above, the heat pump part 200 comprises a compressor 211,which preferably also acts as a pump. The compressor 211 is connected toa four-way valve 212, arranged to control the function of the heat pumppart 200 to be either a cooling or a heating heat pump with respect tothe secondary side 300. In heating operation, the internal heat mediumflow of which is illustrated using arrows in FIGS. 1a -1 c, the four-wayvalve 212 directs the heat medium to circuit 250, for delivering heatvia heat exchanger 215 to the secondary side 300. Returning therefrom,the heat medium passes circuit 240, comprising expansion valve 242 andnon-return valve 241, after which the heat medium passes the heatexchanger 214 and returns, via circuit 220 and the four-way valve 212,back to the compressor 211.

On the other hand, in a cooling operation of the heat pump part 200, theflow of which is illustrated using arrows in FIG. 1d , the four-wayvalve 212 is set so that the internal heat medium flowing out from thecompressor 211 is directed to circuit 220 and then heat exchanger 214,for delivering heat to the primary side 400. Thereafter, the heat mediumpasses circuit 230, comprising expansion valve 232 and non-return valve231, after which it passes to circuit 250 and heat exchanger 215 forabsorbing heat from the secondary side 300. Thereafter, the heat mediumpasses again, via the four-way valve 212, back to the compressor 211.

The non-return valves 231, 241 make sure that either expansion valve 232or expansion valve 242 is passed, depending on the flow direction of theinternal heat medium. This construction is a simple yet robust one forachieving reversibility of the heat pump part 200.

Namely, it is preferred that the heat pump part 200 is reversible, inother words it can be set in a heating mode, delivering thermal energyfrom the primary side 400 to the secondary side 300, and in a coolingmode, delivering thermal energy from the secondary side 300 to theprimary side 400. The reversibility may be provided using other valvearrangements than the one illustrated, for exemplifying reasons, in thefigures. The control means 500 is arranged to control the heat pump part200 to, for each particular point in time, be either in a heating orcooling mode.

According to a preferred embodiment, the control means 500 is arrangedto, in at least one such secondary-side heating operating mode, measurethe temperature of the said primary heat sources or sinks, and tocontrol the said valve means 421, 431, 451 to selectively direct theprimary-side heat medium to only the primary heat exchanging means withthe highest temperature, or to several of said primary heat exchangingmeans with the highest temperatures, such as the two heat sources thatare warmest for the time being.

Preferably, the primary-side heat medium is selectively directed to onlythe primary heat exchanging means that is available for providing heatto the heat pump circuit and associated with the primary heat source orsink with the highest temperature, or to several of said primary heatexchanging means that are available for providing heat to the heat pumpcircuit and associated with the primary heat source or sink with thehighest temperatures.

Herein, the expression “available for providing heat to the heat pumpcircuit” means that the primary heat source or sink in question issufficiently warm so as to be able to heat, via heat exchange, at leastone heat medium in the heat pump circuit 210, 220, 230, 240, 250, 310,320, 410, 420, 430, 440, 450, 460 with the purpose of providing heat toat least one of the secondary heat sources or sinks as described above.This may mean that the primary heat source or sink in question is warmerthan a primary-side heat medium flowing, in a primary-side heat pumpcircuit 410, 420, 430, 440, 450, 460, past a heat exchanger 214 of aninner-loop heat pump circuit 210, 220, 230, 240, 250, as is illustratedin FIGS. 1a -1 c. For instance, such primary-side heat mediumtemperature may be measured immediately downstream of such a heatexchanger 214 using an optional temperature sensor 263 and compared tothe measured temperature of the primary-side heat source or sink. Thismay, alternatively, in the case in which the inner-loop circuit and theprimary-side circuit share one and the same heat medium, mean that theprimary heat source of sink in question is warm enough to be determinedby the control means 500, based upon some predetermined condition, to beable to provide efficient heating given the current operating state ofthe heat pump circuit. Such condition is preferably determined basedupon temperature measurements of the heat medium flowing in the heatpump circuit.

It is noted that the temperature of the primary heat sources or sinkscan be measured directly or indirectly, as described above.

Using such a heat pump system 100, with a valve system for selectivelydirecting a primary-side heat medium to several different primary-sideheat sources or sinks, and actively selecting the warmest one or onesfor transferring thermal energy to the heat pumping function of the heatpump system, the system can be allowed to always operate at a highefficiency. In particular, it is possible to achieve such highefficiency across a broader power interval, and preferably withouthaving to use a top-up heat source (such as electric heating) to handlepower requirements peaks.

According to a preferred embodiment, the control means 500 is arrangedto, in at least one mode of operation, not direct the primary-side heatmedium to all primary heat exchanging means 422, 433, 452 that areavailable for providing heat to the heat pump circuit, but only to asubset of available such primary heat exchanging means. To take a simpleexample, in case a system has access to both an outdoors air heat sourceand a ground heat source, both of which are available since they arewarm enough, the control means may direct the heat medium only to thecorresponding heat exchanger 422 of the outdoors air heat source, sincethis heat source is warmer than the ground heat source. Since there maybe many different heat sources or sinks available to the system, theselection may be more complex than this simple example.

In a first preferred alternative, the control means 500 is arranged tofirst evaluate, by temperature measurement as described above, whichprimary heat exchanging means 422, 433, 452 are available for providingheat to the heat pump circuit, and then to select to which of suchavailable primary heat exchanging means to direct the primary-side heatmedium. Hence, in this case only available heat sources or sinks areconsidered for selection, and the selection is performed from availablesuch heat sources or sinks as a subset of one or several such availableheat sources or sinks.

In a second preferred alternative, the control means 500 is arranged tofirst select to which primary heat exchanging means 422, 433, 452 todirect the primary-side heat medium, namely to the heat exchanging meansof one or several warmest heat sources or sinks, as described above.Thereafter, the control means 500 is arranged to adjust a temperature ofthe heat pump circuit 210, 220, 230, 240, 250, 310, 320, 410, 420, 430,440, 450, 460 so as to be able to accept heat from the selected one orseveral primary heat exchanging means. This is hence the other wayaround as compared to the first preferred alternative—instead ofselecting among available heat sources or sinks, the selection isperformed first, and then the selected heat sources or sinks are madeavailable by means of a suitable temperature adjustment in the heat pumpcircuit. This is particularly advantageous when high heating power isrequired, for instance in a secondary-side heating operation mode inwhich tap water is to be heated as quickly as possible. Then, moreprimary heat sources or sinks can be recruited for maximum power, whileadjusting down the said heat pump circuit temperature so as to be ableto harvest the heat provided by the selected heat source or sources evenin case at least one of the selected heat sources provides a lowertemperature than what is exploitable without such a temperatureadjustment. In particular, it is preferred to, in reaction to atemporary increase in heating power requirements, recruit at least oneaddition heat source or sink the temperature of which is lower thancurrently exploited heat sources or sinks.

To be more specific, we take the particular case, described above, inwhich the heat pump circuit 210, 220, 230, 240, 250, 310, 320, 410, 420,430, 440, 450, 460 comprises an inner loop heat medium circuit 210, 220,230, 240, 250, in turn comprising the compressor 211, the expansionvalve 232, 242 and the inner loop heat exchanger 214, which heatexchanger 214 is arranged to thermally communicate with a separateprimary-side heat medium circuit 410, 420, 430, 440, 450, 460, in turncomprising the primary exchanging means 422, 433, 452. In this case, thecontrol means 500 is preferably arranged to perform the said adjustmentof a temperature of the heat pump circuit by adjusting a temperature ofthe heat medium flowing through the said inner loop heat exchanger 214.Such temperature adjustment may be based upon a temperature measurementfrom optional temperature sensor 216 arranged immediately upstream,and/or possibly immediately downstream, of the heat exchanger 214 inquestion. Hence, the temperature of the inner-loop heat medium isadjusted to a temperature which is lower than the one delivered from theprimary-side heat pump circuit to the heat exchanger 214, making itpossible for the primary-side heat medium to heat the inner-loop heatmedium. It is understood that, in particular in case there are severalselected primary heat sources or sinks, the primary-side heat mediumdelivered to the heat exchanger 214 may have a temperature which isdifferent from the temperature of each individual heat source or sink.Therefore, the temperature measured by sensor 216 may be compared to atemperature measured by sensor 462 or 463. In general, the temperatureof the inner-loop heat medium which is heat exchanged to theprimary-side heat medium is adjusted to a temperature which is lowerthan the selected heat source or sink with the lowest temperature.

In particular, it is preferred that the control means 500 is arranged toadjust said temperature of the inner-loop heat medium flowing throughthe said inner loop heat exchanger 214 by adjusting the power of thecompressor 211 and/or the power of a separate pump (in case thecompressor 211 is supplemented by such an additional pump). Thisadjustment may be performed as a regulation loop, using temperaturereadings from sensor 216 in a feedback loop. In addition to controllingthe compressor 211 and/or such a pump, or instead of such control, anopening of the expansion valve 242 can be controlled so as to achievesuch an inner-loop heat medium temperature. The regulation of theexpansion valve 242 may be performed in a similar feedback loop, or sucha feedback loop may be implemented using control of both the compressor211 and/or said pump, as well as the expansion valve 242.

During such a regulation, it is preferred that the control of thecompressor 211 is performed so as to achieve a desired system 100 power,while the expansion valve 242 is controlled so as to achieve a desiredheat medium temperature, as described in further detail below.

A similar regulation can be performed of the shared heat medium in thecase in which the inner-loop and primary-side circuit share one and thesame heat carrier. Then, the temperature of the heat medium may bemeasured using temperature sensor 216 and the compressor 211 and/or apump and/or the expansion valve 242 may be controlled so as to achieve aheat medium temperature making it possible for the heat medium to beheated when passing the corresponding heat exchanging means of theselected primary heat sources or sinks.

In particular, in the preferred case that the primary heat sources orsinks to which the said valve means is arranged to selectively directthe primary-side heat medium comprise at least one heat source or sinkwhich is outdoors air and at least one heat source or sink which is theground (as illustrated in the figures), it is preferred to only cool theground, in particular a bore hole 431, when the ground temperature, asmeasured by sensor 432, is higher than the outdoors air, as measured bysensor 412. This also results in a simple and efficient way of notcooling the ground unnecessarily, which provides for a more efficientuse of available thermal energy in the ground.

In case exhaust air is available via conduit 453, and in case thatexhaust air is warmer than the outdoors air, it is preferred to use heatsource 452 instead of, or, preferably, in addition to, heat source 422,at least as long as the heat source 433 is cooler than heat source 452.

Correspondingly, according to a preferred embodiment, the control means500 is further arranged to, in a secondary-side cooling operating mode,control the valve means 421, 431, 451 to selectively direct theprimary-side heat medium to only the primary heat exchanging means withthe lowest temperature, as measured by the temperature sensors 423, 424,425, 432, 434, 435 and/or 454. This will provide high operatingefficiency.

In the preferred embodiment in which several primary-side heat sourcesor sinks are used during said secondary-side heating operation mode, itis further preferred that the control means 500 is arranged toselectively direct primary-side heat medium to at least two of theprimary heat exchanging means with higher temperatures than apredetermined minimum temperature. In particular, it is preferred thatall, or at least two, of the primary heat sources that are warmer, forthe time being, than the said predetermined minimum temperature areused. Preferably, the said predetermined minimum temperature is between0 and 10° C., more preferably between 2 and 5° C. In particular, it ispreferred that outdoors air (source 422) is not used as a heat source incase the temperature of the outdoors air is less than about 2° C. abovethe average current temperature of the ground when a ground heat source433 is available. The average current temperature can be measured in away which is conventional as such.

In a similar preferred embodiment for use during the mentionedsecondary-side cooling operation mode, in which several primary-sideheat sources or sinks are used during said secondary-side coolingoperation mode, it is further preferred that the control means 500 isarranged to selectively direct primary-side heat medium to at least twoof the primary heat exchanging means with lower temperatures than apredetermined maximum temperature. In particular, it is preferred thatall, or at least two, of the primary heat sources that are cooler, forthe time being, than the said predetermined maximum temperature areused. Preferably, the said predetermined maximum temperature is between5 and 15° C., more preferably between 7 and 10° C. In particular, it ispreferred that outdoors air (source 422) is not used as a cool source incase the temperature of the outdoors air is more than about 2° C. belowthe average temperature of the ground when a ground cool source 433 isavailable.

In particular, the following different secondary-side heating operatingmodes are envisaged:

1. During a cold season, such as winter in tempered climates, when thereis a need for heating indoors air and tap water, and when the outdoorsair is cooler than the ground surrounding the bore hole 431, thermalenergy is only drawn from the ground. In other words, the three-wayvalve 421 is set as shown by the flow arrows in FIG. 1 b, with left andright outlets open and the top outlet (as seen in the orientation of thefigures) closed. At the same time, the three-way valve 431 is set withits left and right outlets open, but the bottom one closed. Then, theprimary-side heat medium flows as is illustrated in FIG. 1 b. This way,the more efficient heat from the ground (as compared to from theoutdoors air) can be used for heating of the construction. It is notedthat, in this mode, the exhaust air may be heated also, if available.This is then performed by the three-way valve 451 having its right andbottom outlets open and its left outlet closed, which is alsoillustrated in FIG. 1 b.

2. During a warm season, such as summer in tempered climates, when theoutdoors air is warmer than the ground surrounding the bore hole 431,thermal energy is only drawn from the outdoors air. Hence, the three-wayvalve 421 is set with its left and top outlets open, and its rightoutlet closed, while three-way valve 431 is set with its left and bottomoutlets open, and its right outlet closed. Then, flow of primary-sideheat medium will be as in FIG. 1 a. In this case, as well as inoperating mode 1, the exhaust air may also be used, such as illustratedin FIGS. 1a and 1 b.

3. In case the temperature difference between two heat sources, such asthe outdoors air and the ground, is less than a predetermined value,such as 5° C., it is preferred that only heat sources that do notrequire an operating fan, such as the ground heat exchanger 433 and theexhaust air heat exchanger 452 in the particular case illustrated in thefigures, are used.

4. During unusually large requirements for heating at the secondary side300, the three-way valve 421 has its left and top outlet open, while itsright outlet is closed, and the three-way valve 431 has its left andright outlet open, while its bottom outlet is closed. Then, the flowwill be as illustrated in FIGS. 1c and 1 d, and both primary-side heatsources will be used for heating at a heating power which is higher thana normal heating power provided only using one of the heat sources. Thisoperation mode is also useful when there is a need for secondary-side300 heating and the outdoors air is warmer than the ground (in thiscase, a large temperature difference is allowed between outdoors air andthe ground). Then, the outdoors air heat exchanger 422 will be passedfirst by the primary-side heat medium, such that it is preheated by theoutside air, after which the hence preheated heat medium passes the borehole 431 in the ground. This way, a heated primary-side heat medium willresult for heat exchange in heat exchanger 214 with the inner circuit210, 220, 230, 240, 250, while at the same time the ground surroundingthe bore hole 431 will be recharged with heat.

5. During times when the ground surrounding the bore hole 431 is coolerthan the outdoors air, and when there is no need for heating or coolingat the secondary side 300 for the time being, it is preferred that thethree-way valve 421 is set with its left and top outlets open, while itsright outlet is closed, and that the three-way valve 431 is set with itsleft and right outlets open, while its bottom outlet is closed, why theprimary-side heat medium flow is as illustrated in FIGS. 1c and 1 d. Atthe same time, the inner circuit 210, 220, 230, 240, 250 flow isinactivated, by the compressor 211 being switched off, resulting in noheat exchange at heat exchanger 214. The result is that thermal energyis moved from the outdoors air to the bore hole 431, effectivelyrecharging the ground surrounding the bore hole 431 with heat, which maybe used during the cold season for heating of the construction. Hence,this is a bore hole 431 recharging operation mode. It is noted that thethree-way valve 411 (see below) in this case has its left and rightoutlets open and its top outlet closed, so that no thermal transfer isperformed between the primary 400 and secondary 300 sides.

The bore hole 431 recharging mode is particularly preferred for alreadyexisting bore holes 431 that are under-dimensioned, such as in terms ofbore hole 431 depth, for the heating requirements of the saidconstruction. In this case, it is a method according to a preferredembodiment of the present invention comprises an initial step in whichthe system 100 components are installed using said already-existing borehole 431, and in that the method further comprises a step in which thebore hole 431 is recharged as described above under operating mode 5.Preferably, the temperature of the heat medium leaving the bore hole 431is measured, and a trend is monitored. Recharging mode is then initiatedas needed based upon the said trend, so that the bore hole 431 isrecharged when the ground surrounding the bore hole 431 becomes toocool.

In addition to the modes 1-5 described above, the exhaust air heatexchanger 452 can be used as a heat source whenever so is desirable, toincrease the efficiency of the system 100.

As mentioned above, the present invention further encompasses a methodfor controlling the heat pump device 100. Such a method comprises a stepin which the control means 500 measures the temperature of saidsecondary heat sources or sinks, as well as a further step, in the abovedescribed secondary-side heating operating mode, in which the controlmeans 500 controls the valve means 421, 431 to selectively direct theprimary-side heat medium to only the primary heat exchanging means withthe highest temperature, or to several of said primary heat exchangingmeans having the highest temperatures.

According to a preferred embodiment, the speed of the compressor 211 canfurthermore be dynamically controlled, by the control means 500.Furthermore according to this embodiment, a respective opening size ofat least one, preferably each, of the expansion valves 232, 242 isadjustable, also by the control means 500. Then, the control means 500is arranged to control the instantaneous power of the heat pump system100 by controlling the instantaneous speed of the compressor 211, andthe control means 500 further being arranged to, at the same time,control an output temperature of the heat medium (in the exemplifyingembodiment illustrated in the figures by the internal heat medium)flowing out from the respective expansion valve 232,242 by controllingthe opening of the expancion valve 232, 242 in question given thecontrolled speed of the compressor 211.

A compressor 211 speed increase will result in an increased pressuredifference across the compressor 211, together with an increasedtemperature of the inner heat medium flowing out from the compressor211. A more open expansion valve 232, 242 will result in a greater flowof heat medium out from the expansion valve 232, 242 in question but atthe same time lower temperature of such heat medium. Hence, by settingthe speed of the compressor 211 to correspond to a desired heat pumpingpower and then adjusting the expansion valve 232, 242 to a desiredoutput temperature of the inner heat medium, a heat medium of aparticular temperature (for heat exchanging with secondary-side heatconsumers) is produced at a desired heating power.

This results in a flexible heating power. During “normal” operation, thecompressor 211 may be set to a non-maximum speed, meeting the heatingpower needs of a “normal” state of the construction. However, duringheavier heating power requirements, the compressor 211 speed can beincreased to meet the higher requirements while still producing heatmedium of a desired temperature using a controlled smaller expansionvalve 232, 242 opening. As a consequence, the heat pumping system 100can be designed without the need for an additional top-up heatingsource, such as an electrical direct heating source, for handling peakheating operation situations, and still providing for efficientoperation during most operation situations. This provides for bettereconomy and environmental concern. Furthermore, during times when theconstruction cannot accept heating at a normal rate without beingoverheated, the compressor speed can be controlled down to meet suchdecreased heating requirements rather than being completely switchedoff.

Further advantages will be explained in connection to the followingpreferred embodiments.

It is noted that a method according to the present invention preferablycomprises a corresponding method step, in which the speed of thecompressor 211 is controlled by the control means 500, so as to achievea certain heat pumping power of the heat pump system 100. Furthermore,the method comprises a step in which an opening of the expansion valve232, 242 is adjusted by the control means 500 so as to achieve a certainoutput temperature of inner heat medium flowing out from the expansionvalve 232, 242 in question, given the controlled speed of the compressor211.

That the expansion valve 232, 242 is controlled “given the controlledspeed of the compressor 211” means that the compressor 211 is controlledto a particular speed, and that the expansion valve 232, 242 iscontrolled to achieve the said output temperature with the compressor211 speed as a given variable.

According to one preferred embodiment, illustrated in the figures, theheat pump system 100 comprises at least two secondary heat exchangingmeans 314, 315, 316 as explained above, and the heat pump system 100further comprises a valve means 311, 312, 313 as described above,arranged to, under control from the control means 500, selectivelydirect the secondary-side heat medium to one or several of saidsecondary heat exchanging means 314, 315, 316, preferably for heatingone or several corresponding secondary-side heat consumers. Furthermore,the control means 500 is arranged to control the said output temperatureof the heat medium flowing out from the expansion valve 242 based uponwhat secondary heat exchanging means 314, 315, 316 is or are used forthis heat exchange for the time being.

Hence, if a low-temperature floor heating system circuit 330 is activeas the only used secondary-side heat consumer, the output temperature iscontrolled to a relatively low value, such as between 20-50° C., with acorresponding large flow velocity of the heat medium flowing out fromthe expansion valve 242. On the other hand, if tap water 343 is to beheated, the output temperature is controlled to a relatively high value,such as between 50-70° C., with a corresponding small flow velocity ofthe heat medium flowing out from the expansion valve 242. Hence,depending on what secondary-side heat consumer(s) is or are to be used,the temperature of the heat medium can be altered without modifying theoverall operating power of heat pumping function of the system 100. Whenthere are several secondary-side heat consumers, it is preferred that adesired heat exchanging temperature for the highest temperature-desiringsecondary-side heat consumer is selected as the desired outputtemperature from the expansion valve 242. In the latter case, a feedbackor shunt valve arrangement (not shown in the figures) can be used tolower the temperature of the secondary-side heat medium flowing throughlower temperature-requiring secondary-side heat consumer heatexchangers.

In particular, it is preferred that the heat medium circuit 210, 220,230, 240, 250, 310, 320, 410, 420, 430, 440, 450, 460 comprises at leasttwo secondary heat exchanging means 314, 315, 316. Then, the system 100can be operated in a first secondary-side heating operating mode, inwhich a secondary heat exchanging means 314 (or 315 in combination with331 and 332) is used to transfer thermal energy to indoors air. Further,the system 100 can be operated in a second secondary-side heatingoperating mode, in which a secondary heat exchanging means 316 is usedto transfer thermal energy to hot tap water 343. Under theseprerequisites, the opening of the expansion valve 242 is adjusted sothat the output temperature of heat medium flowing out from theexpansion valve 242 is higher in the second secondary-side heatingoperating mode than in the first secondary-side heating operating mode.Such different secondary-side heating operating modes can then be usedalternatingly, such as using an alternation time interval of between 5and 30 minutes, to over time provide heat to both indoors air and hottap water.

According to a particularly preferred embodiment of the presentinvention, the said control of the expansion valve 232, 242 opening is afeedback control which is based upon a measurement value from arespective temperature sensor 233, 243, comprised in the heat pump 100system and arranged downstream of the respective expansion valve 232,242 opening. The measurement value is provided to the control device500, which then dynamically control the expansion valve 232, 242 inquestion in a feedback manner, so as to keep the desired outputtemperature of the expansion valve 232, 242 depending on the currentoperation mode of the heat pump system 100.

According to one preferred embodiment, the control of the compressor 211speed is controlled to meet a desired total heat pumping power of thesystem 100, and based upon a given current temperature of one or severalprimary-side heat sources or sinks. More particularly, in thisembodiment the heat pump system 100 comprises at least one temperaturesensor 423, 424, 425, 432, 434, 435, 454, arranged to measure thetemperature in a respective one of said primary heat exchanging means orof the corresponding primary-side heat medium after heat exchange in theprimary heat exchanging means in question. The system 100 can then beoperated in a first primary-side heating operating mode, in which atleast one of said primary heat exchanging means 433 is used to transferthermal energy from the ground or a water body, such as a lake, as wellas in a second primary-side heating operating mode, in which at leastone of said primary heat exchanging means 422 is used to transferthermal energy from the outdoors air. According this embodiment, thecontrol device 500 is arranged to then control the speed of thecompressor 211 so that the total instantaneous heating power requirementfor the heat pump system 100 is met given the current measuredtemperature in the said primary heat exchanging means of theprimary-side heat medium after the heat exchange performed in thecurrently used primary-side heating operating mode. It is noted that thecompressor 211 speed required to meet a particular total powerrequirement is different for these two primary-side heating operationmodes, using different temperatures of the primary-side heat mediumflowing through the heat exchanger 214. Alternatively, the temperatureof the primary-side heat medium can also be measured at the heatexchanger 214, using an optional temperature sensor 462.

A normal building, in particular a small one- or two family house,typically has a thermal energy requirement that varies heavily overtime. Sometimes, the energy requirement will be zero, while peak energyrequirements may be high, with the upper limits being determined by, forinstance, the size of the house, the temperature difference betweenoutdoors air and indoors air, as well as hot tap water usage. For anormal one- or two family house located in tempered climates such as inthe Nordic countries, a typical thermal energy requirement is betweenabout 0-12 kW at any given point in time over the year.

Conventionally, to handle peak requirements, a geothermal heat pump iscombined with a direct electrical heating which is only used during peakproduction. When using the heat pump system 100 of the presentinvention, it is preferred not to use any such additional heating systemfor use only during peak production, and in particular not such a directelectrical heating system, arranged to electrically heat indoors airdirectly or via a liquid radiator circuit, or hot tap water, at all.Instead, it is preferred to use control of the compressor 211 speed asdescribed above to adjust the power of the system 100 to handle shiftingheating (or cooling) needs.

Another conventional alternative is to use an accumulation tank, such asan additional water tank, to store thermal energy for use during peakrequirements. According to the present invention, it is preferred not tohave such an accumulation tank, apart from a possible hot tap water tank342. According to one embodiment, there may however exist anaccumulation tank (not shown in the figures) along circuit 310, fromwhich all or some of the secondary-side heat exchangers 314, 315, 316draw their heat and/or cold.

In the following, particular examples are described of operation of theheat pump system 100 in accordance with the present invention,especially with respect to the variability of the compressor 211 and theexpansion valve(s) 232, 242.

In a first example, the outdoors temperature is a bit cooler than whatis normal for the location at which the construction is situated, saythat the outdoors temperature is 0° C. The current heating requirementsof the building in question are high, since a user of the building hasrecently taken a bath, why there is a need to reheat relatively largeamounts of hot tap water. Also, the weather forecast delivered to thecontrol means 500 indicates that the outdoors temperature is about tofall to even lower temperatures during the coming hours. Hence, as aresult the control means 500 initiates an operating mode in whichmaximum heat is to be delivered to both the heat exchangers 314 and 315,and also to the heat exchanger 316 for heating hot tap water. At themoment, measured temperatures indicate to the control means 500 thatenergy can be efficiently drawn from both the outdoors air and the borehole 431. Therefore, the primary-side heat medium is circulated passedboth heat exchangers 422, 433, to deliver thermal energy to the innercircuit 210, 220, 230, 240, 250 via the heat exchanger 214. Thecompressor 211 is set to maximum speed, providing maximum heat pumpingpower, and the expansion valve 242 is set, during each point in timeduring operation, so that the temperature is suitable for heating eitherindoors air or hot tap water, in case these two secondary-side heatingactions are performed one at a time (preferably in an alternatingmanner, in which the valves 311, 312, 313 are activated so that thesecondary-side heat medium is delivered to the heat exchangers 314/315or 316 alternatingly, every other predetermined time period). Forheating indoors air, the expansion valve 242 will be set to a more openposition than is the case for when heating tap water, as explainedabove. In case both heat exchangers 314/315 and 316 are operatedsimultaneously, the expansion valve 242 may be set so that thesecondary-side heat medium assumes a temperature which is suitable forheat exchanging with the indoors air heat exchangers 314 or 315.

In a second example, the expansion valve 232, 242 is operated acrossdifferently open states to achieve different aims. For instance, if anon-zero heat pumping action is instead desired, the expansion valve232, 242 must provide a pressure difference between heat medium upstreamand downstream of the expansion valve 232, 242. In this latter case, theexpansion valve 232, 242 may be set by the control means 500 to anysetting between 0-50% open.

In case the compressor 211 operates at full speed, a 40% open expansionvalve 232, 242 may, in an exemplifying case, result in 80° C. inner heatmedium. In case the compressor 211 operates at 50% of full speed, theexpansion valve 232, 242 may be set to 20% open, and as a result provide85° C. inner heat medium with a total instantaneous power of about halfof the full speed example. Hence, the same or nearly the same heatmedium temperature can be achieved using various heat pumping powers.

In a third example, it is summer in a Nordic country. The outdoorstemperature is 25° C., and there is no need for indoors heating.However, the need for hot tap water is higher than normal. Also, thereis a need for heating of a pool 342. Thermal energy is then drawn fromthe outdoors air only (providing higher efficiency and avoiding coolingof the ground), via heat exchanger 422, and is delivered at medium powerand high temperature, by control of the compressor 211 and the expansionvalve 242, to respective secondary-side tap water and pool heatexchangers. In case cooling of indoors air is required,intermittent/interchanging operation may be performed by the controlmeans, in which indoors air is cooled via corresponding secondary-sideheat exchangers and pushing thermal energy into only the bore hole 431(recharging the bore hole 431) by setting valves 421, 431 at illustratedin FIG. 1b while running the heat pump part 200 as illustrated in FIG. 1d, during every other predetermined time period, and in which tap waterand pool water is heated during every other predetermined time period,drawing thermal energy only from outdoors air by setting valves 421, 431as illustrated in FIG. 1 a. The power and heat medium temperature isadjusted so as to suit the particular requirements during every suchpredetermined time period.

In particular, the power of the compressor 211 is controlled down in theheating sequence of this operating mode in case there is a risk ofoverheating the tap water or the pool water. This will avoid the heatpump system 100 to have to be shut down for security reasons, which isotherwise a risk with a conventional system.

In general, it is preferred that a variable compressor 211 according tothe present invention is dimensioned so that it runs at peak compressorefficiency at or near a “normal” heat pump requirement of theconstruction, and so that it also has capacity of delivering a maximumheat pump power which covers most operating prerequisites. For instance,if a “normal” power requirement is about 5 kW, the compressor 211 shouldrun at or near its peak efficiency at a speed corresponding to 5 kW whenusing a 5° C. primary-side heat medium (which would be a normaltemperature in the present example, using the bore hole 431 located inthe Stockholm area). The electrical power required to run the heat pumpsystem 100 at this power and under those prerequisites would be about 1kW or thereabouts.

The heat pump system 100 also allows a direct cooling operation withoutheat pumping action (“free cooling”), according to the following. Inthis embodiment, the heat pump system 100 comprises a respectivetemperature sensor 423, 424, 425, 432, 434, 435, measuring thetemperature in the said primary heat exchange means 422, 433 or of theprimary-side heat medium after heat exchange in the primary heatexchange means 422, 433. Then, the heat pump system 100 can be operatedin a first secondary-side cooling operating mode, in which the heatmedium cools indoors air. In this operating mode, the control device 500is arranged to control a valve means 411 comprised in the primary side400 of the heat pump system 100 so that the heat pump part 200 isbypassed in the said first secondary-side cooling operation and when themeasured temperature in the used primary heat sink is lower than apredetermined temperature value. A circulation pump 413 in the circuit410 is used to provide the primary-side heat medium to heat exchanger412, which in turn is arranged to transfer thermal energy from thesecondary-side heat medium in circuit 310 to primary-side heat medium incircuit 410. This way, the cooled primary-side heat medium will, viaheat exchanger 412, achieve cooled primary-side heat medium, which isthen used to cool the indoors air, for instance via heat exchangers 314and/or 315. In this case, which is illustrated in FIG. 1d , the saidpredetermined temperature value may be as high as about 4-5° C. lowerthan the desired indoors air. Since no heat pumping is required in thisoperating mode, less energy will be spent while still achieving acomfortable indoors climate, using the same heat pump system 100 as iscapable of providing flexible and efficient thermal energy management asdescribed in the numerous embodiments explained above.

According to one preferred embodiment of the present invention, the heatpump system 100 can be used in a method for monitoring valve leaks inthe heat pump system 100. In this aspect, there are at least three heatexchanging means 314, 315, 316, 422, 433, 452, as described above,arranged to transfer thermal energy between the secondary, inner and/orprimary heat medium and a respective heat source or sink selected fromoutdoor air, a water body, the ground, indoor air, pool water or tapwater. There are also valve means 311, 312, 313, 421, 431, 451, arrangedto selectively direct the heat medium to at least two of said heatexchanging means. This has been described in detail above.

In this embodiment, the heat pump system 100 comprises respective pairsof temperature sensors 314 a, 314 b; 315 a, 315 b; 316 a, 316 b; 424,425; 434, 435; and 455; 454, arranged both upstream and downstream of atleast one, preferably each, of said heat exchanging means 314, 315, 316,422 433, 452. Then, the determination by the control means 500 of whichprimary and/or secondary heat exchanging means 314, 315, 316, 422, 433,452 to direct the corresponding heat medium to, as described above fordifferent operating modes, is performed based upon temperaturemeasurement values comprising at least one value read from said sensorsof said temperature sensor pairs. Further, when respective heat mediumis not directed to a certain one of said heat exchanging means, thecontrol means 500 is arranged to read a measured temperature valueupstream and measured temperature value downstream of the certain heatexchanging means in question, to compare these values to each other andto set off an alert in case the values differ by more than apredetermined value.

Namely, such a read temperature difference indicates that there is aleakage in a valve arranged to direct heat medium to the heat exchangerin question, and such an alert is preferably arranged to warn amaintenance responsible person that the valve in question may needservice or replacement. The valve may be any type of valve, such as ashut-off valve or a three-way valve.

For example, in case no heat medium is to be delivered to heat exchanger314, the shut-off valve 311 is activated, with the purpose of stoppingsecondary-side heat medium to flow past the heat exchanger 314. Then,temperature sensors 314 a, 314 b are read, and if there is a detectedtemperature difference between the values read from these sensors, whichdifference is larger than a predetermined value, it is likely that theshut-off valve does not function properly, and the alert is set off.

Another example is that the temperature sensors 424, 425 are used, asdescribed above, to determine that the heat exchanger 422 is not be usedin the current operating mode. Therefore, the three-way valve 421 is setinto the position in which its left and right outlets are open and itstop outlet is closed, resulting in that no primary-side heat mediumflows through circuit 420 past heat exchanger 422.1n case the controlmeans 500 thereafter reads a temperature difference between sensors 424and 425, this would indicate that the three-way valve is not workingproperly, and an alarm is set off with respect to the three-way valve.

Since the said temperature difference measuring sensors are a part ofthe heat pump system 100 anyway, using them to detect a malfunctioningvalve adds only very little additional complexity to the system 100.

According to one preferred embodiment, the said temperature differenceis measured and considered by the control means 500 only a certain timeperiod, such as at least 5 minutes, after the respective heat exchangerhas been inactivated, in other words that control means 500 hasdetermined that no heat medium is to be directed to the respective heatexchanger. This will use the computing power of the control means toavoid false alarms being set off in connection to the disconnection ofparticular heat exchangers.

According to another preferred embodiment, the control means 500measures the said temperature difference repeatedly over time when thecorresponding heat exchanger is disconnected, in other words when itdoes not receive any heat medium, and sets off said alert in case theread absolute temperature difference increases with more than apredetermined value, preferably at least 2° C., between a referencereading, measured previously but after the disconnection of the heatexchanger in question, that is when the heat medium was disconnected tothe heat exchanger in question, and a later reading, measured after thereference reading while the heat exchanger is still disconnected.

According to one preferred embodiment, the temperature value under thecurrently used operating mode is measured over an extended time period,so as to provide the control means 500 with statistical data over howthe measured temperature difference varies. Then, the alarm is set offin case the measured temperature difference deviates more than apredetermined number of standard deviations from zero.

The alarm can, for instance, be in the form of a digital messageautomatically sent to a predetermined SMS, e-mail or other type ofpreregistered recipient.

Hence, a method according to the present invention will, in this case,comprise a step in which the control means 500 reads temperaturemeasurement values comprising at least one value read from saidtemperature sensor pairs and, based upon these values, determines towhat heat exchanging means the heat medium is to be directed. Then, sucha method further comprises a step in which, when heat medium is notdirected to a certain heat exchanging means the control means reads ameasured temperature value upstream and downstream of the certain heatexchanging means, compares these values to each other and sets off thesaid alert in case the values differ by more than said predeterminedvalue.

In the alternative system described above, in which the heat pump part200 and the primary-side part 400 share one and the same heat medium,the heat exchanger 214 is hence not used. Furthermore, in such analternative system, the heat pump part 200 is preferably not reversible,but only arranged for heating. The free cooling circuit 410 is also notused.

A system and a method according to the above solve the initiallymentioned problems.

Above, preferred embodiments have been described. However, it isapparent to the skilled person that many modifications can be made tothe disclosed embodiments without departing from the basic idea of theinvention.

For instance, it is realized that the details of the heat pump system100 as illustrated in the figures, such as position of temperaturesensors, combination of primary/secondary heat sources or sinks, etc.can vary, depending on circumstances.

The embodiments illustrated in the figures each comprise quite manydetails. This may be the case in an actual embodiment of the presentinvention. However, it is also realized that the reason for the figuresbeing detailed is to illustrate several different aspects of theinvention. Hence, embodiments of the invention may comprise only morelimited number of details, as defined by the claims. For instance, theexhaust air heat exchanger 452 may or may not be used in combinationwith the other features shown in FIGS. 1a -1 d.

In general, the above described embodiments and features of the presentheat pump system 100 and methods are freely combinable, as applicable.For instance, one or several of the primary-side heat sources or sinkscan be dynamically selected for exploitation of thermal energy asdescribed above, while at the same time the compressor and expansionvalve can be controlled dynamically so as to at all times meet aninstantaneous required total heat pumping power and heat mediumtemperature for a currently used secondary-side application. This way,an optimal use of primary-side heat sources or sinks can be combinedwith a desired secondary-side energy use, in a way which functionallydisconnects the primary side 400 from the secondary side 300 in thesense that these sides can be operated in a way in which one side isoperated independently of the other so as to achieve the particularrespective current operating goals.

Furthermore, what has been described above in relation to the system 100according to the present invention is also freely applicable,correspondingly, to the method according to the present invention, andvice versa, as applicable.

Hence, the invention is not limited to the described embodiments, butcan be varied within the scope of the enclosed claims.

1. Heat pump system comprising a heat medium circuit in turn comprisingat least three heat exchanging means arranged to transfer thermal energybetween the heat medium and a respective heat source or sink selectedfrom outdoor air, a water body, the ground, indoor air, pool water, tapwater or a topmost ground layer, a valve means arranged to selectivelydirect the heat medium to at least two of said heat exchanging means,and a control means arranged to control said valve means, wherein theheat pump system comprises respective temperature sensors both upstreamand downstream of at least one of said heat exchanging means, whereinthe control means is arranged to, based upon temperature measurementvalues comprising at least one value read from said sensors, determineto what heat exchanging means the heat medium is to be directed, whereinwhen heat medium is not directed to a certain heat exchanging means thecontrol means is arranged to read, repeatedly over time, a measuredtemperature value upstream and downstream of the certain heat exchangingmeans, and to set off an alert in case a difference between the readtemperatures increases by more than a predetermined value between areference reading, measured previously but after the disconnection ofthe delivery of heat medium to the heat exchanger in question, and alater reading, measured after the reference reading while the heatexchanger still does not receive any heat medium.
 2. Heat pump systemaccording to claim 1, wherein the predetermined value is at least 2°. 3.Heat pump system according to claim 1, wherein the control means isarranged to measure said temperature values over an extended timeperiod, so as to obtain statistical data over how the measuredtemperature difference varies, and wherein the alarm is set off in casethe measured temperature difference deviates more than a predeterminednumber of standard deviations from zero.
 4. Heat pump system accordingto claim 1, wherein the heat pump system further comprises a compressor,an expansion valve, at least two primary heat exchanging means arrangedto transfer thermal energy between a primary-side heat medium and atleast one of two different primary heat sources or sinks selected fromoutdoor air, a water body or the ground, at least one secondary heatexchanging means, arranged to transfer thermal energy between asecondary-side heat medium and at least one of two different secondaryheat sources or sinks selected from indoors air, pool water and tapwater, a respective temperature sensor arranged to measure thetemperature of each of said primary heat sources or sinks, and a valvemeans arranged to selectively direct the primary-side heat medium to atleast one of said primary heat exchanging means, and wherein the controlmeans is arranged to, in a secondary-side heating operating mode,measure the temperature of said primary heat sources or sinks, and tocontrol the valve means to selectively direct the primary-side heatmedium to only the primary heat exchanging means associated with theheat source or sink with the highest temperature, or to several of saidprimary heat exchanging means associated with the respective heatsources or sinks with the highest temperatures.
 5. Heat pump systemaccording to claim 1, wherein the heat pump system further comprises acompressor, an expansion valve, at least one primary heat exchangingmeans arranged to transfer thermal energy between a primary-side heatmedium and a primary heat source or sink selected from outdoor air, awater body or the ground, at least one secondary heat exchanging means,arranged to transfer thermal energy between a secondary-side heat mediumand a secondary heat source or sink selected from indoors air, poolwater and tap water, and wherein the speed of the compressor can becontrolled, wherein an opening of the expansion valve is adjustable,wherein the control means is arranged to control the power of the heatpump system by controlling the speed of the compressor, and wherein thecontrol means is arranged to control an output temperature of heatmedium flowing out from the expansion valve by controlling the openingof the expansion valve given the controlled speed of the compressor. 6.Method for monitoring valve leaks in a heat pump system comprising aheat medium circuit in turn comprising at least three heat exchangingmeans arranged to transfer thermal energy between the heat medium and arespective heat source or sink selected from outdoor air, a water body,the ground, indoor air, pool water, tap water or a topmost ground layer,a valve means arranged to selectively direct the heat medium to at leasttwo of said heat exchanging means, and a control means arranged tocontrol said valve means, wherein the heat pump system comprisesrespective temperature sensors both upstream and downstream of at leastone of said heat exchanging means, wherein the method comprises a stepin which the control means reads temperature measurement valuescomprising at least one value read from said sensors and, based uponthese values, determines to what heat exchanging means the heat mediumis to be directed, and wherein the method further comprises a step inwhich, when heat medium is not directed to a certain heat exchangingmeans the control means reads, repeatedly over time, a measuredtemperature value upstream and downstream of the certain heat exchangingmeans, and sets off an alert in case a difference between the readtemperatures increases by more than a predetermined value between areference reading, measured previously but after the disconnection ofthe delivery of heat medium to the heat exchanger in question, and alater reading, measured after the reference reading while the heatexchanger still does not receive any heat medium.
 7. Method according toclaim 6, wherein the predetermined value is at least 2°.
 8. Methodaccording to claim 6, wherein the control means measures saidtemperature values over an extended time period, so as to obtainstatistical data over how the measured temperature difference varies,and wherein the alarm is set off in case the measured temperaturedifference deviates more than a predetermined number of standarddeviations from zero.
 9. Method according to claim 6, wherein the saidtemperatures are measured and considered by the control means only acertain time period after the control means has determined that no heatmedium is to be directed to the respective heat exchanger.
 10. Methodaccording to claim 6, wherein the heat pump system is further caused tocomprise a compressor, an expansion valve, at least two primary heatexchanging means for transferring thermal energy between a primary-sideheat medium and at least one of two different primary heat sources orsinks selected from outdoor air, a water body or the ground, at leastone secondary heat exchanging means, for transferring thermal energybetween a secondary-side heat medium and at least one of two differentsecondary heat sources or sinks selected from indoors air, pool waterand tap water, a respective temperature sensor for measuring thetemperature of each of said primary heat sources or sinks, and a valvemeans for selectively directing the primary-side heat medium to at leastone of said primary heat exchanging means, and wherein the methodcomprises a step in which the control means measures the temperature ofsaid secondary heat sources or sinks, and wherein the method furthercomprises a step, in a secondary-side heating operating mode, in whichthe control means controls the valve means to selectively direct theprimary-side heat medium to only the primary heat exchanging means withthe highest temperature, or to several of said primary heat exchangingmeans with the highest temperatures.
 11. Method according to claim 6,wherein the heat pump system is further caused to comprise a compressor,an expansion valve, at least one primary heat exchanging means fortransferring thermal energy between a primary-side heat medium and aprimary heat source or sink selected from outdoor air, a water body orthe ground, at least one secondary heat exchanging means, fortransferring thermal energy between a secondary-side heat medium and asecondary heat source or sink selected from indoors air, pool water andtap water, and wherein the method comprises a step in which the speed ofthe compressor is controlled by the control means, so as to achieve acertain power of the heat pump system, and wherein the method furthercomprises a step in which an opening of the expansion valve is adjustedby the control means so as to achieve a certain output temperature ofheat medium flowing out from the expansion valve given the controlledspeed of the compressor.